The short-term goal of this project is to conduct a feasibility study at Winthrop University Hospital to determine how well extremely obese (BMI > 99%tile corrected for age) children and adolescents can be recruited into an exercise program and evaluated in an efficient fashion, and to identify particular strategies (e.g., medical examination feedback) that can serve as potential benefits to research subjects and their families. In addition investigators will evaluate the effect of the exercise program on physical fitness, insulin resistance, and neurocognitive functioning as well as the relationship between insulin sensitivity and neurocognitive function among adolescents who participate in the exercise program.